objc - minor comment fix up and cleanup.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@138253 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDeclObjC.cpp

@@ -2665,8 +2665,8 @@ Decl *Sema::ActOnMethodDeclaration(
 bool Sema::CheckObjCDeclScope(Decl *D) {
   if (isa<TranslationUnitDecl>(CurContext->getRedeclContext()))
     return false;
-  // Following is also an error. But it is caused my a missing @end
-  // and diagnostic is issued elsewere.
+  // Following is also an error. But it is caused by a missing @end
+  // and diagnostic is issued elsewhere.
   if (isa<ObjCContainerDecl>(CurContext->getRedeclContext())) {
     return false;
   }

lib/Sema/SemaObjCProperty.cpp

@@ -144,7 +144,7 @@ Sema::HandlePropertyInClassExtension(Scope *S,
                                      bool *isOverridingProperty,
                                      TypeSourceInfo *T,
                                      tok::ObjCKeywordKind MethodImplKind) {
-  ObjCCategoryDecl *CDecl = dyn_cast<ObjCCategoryDecl>(CurContext);
+  ObjCCategoryDecl *CDecl = cast<ObjCCategoryDecl>(CurContext);
   // Diagnose if this property is already in continuation class.
   DeclContext *DC = CurContext;
   IdentifierInfo *PropertyId = FD.D.getIdentifier();